Search Publications
Ionization of the venusian atmosphere from solar and galactic cosmic rays
Coates, A. J.; Jones, G. H.; Desorgher, L. +2 more
The atmospheres of the terrestrial planets are exposed to solar and galactic cosmic rays, the most energetic of which are capable of affecting deep atmospheric layers through extensive nuclear and electromagnetic particle cascades. In the venusian atmosphere, cosmic rays are expected to be the dominant ionization source below ∼100 km altitude. Whi…
Seasonal evolution of Saturn's polar temperatures and composition
Fletcher, Leigh N.; Irwin, P. G. J.; Orton, G. S. +7 more
The seasonal evolution of Saturn's polar atmospheric temperatures and hydrocarbon composition is derived from a decade of Cassini Composite Infrared Spectrometer (CIRS) 7-16 µm thermal infrared spectroscopy. We construct a near-continuous record of atmospheric variability poleward of 60° from northern winter/southern summer (2004, Ls
Embedded clays and sulfates in Meridiani Planum, Mars
Bibring, J. -P.; Poulet, F.; Davies, G. R. +4 more
The area of Meridiani Planum on Mars became of particular interest after the detection of coarse-grained, gray hematite, which led to the choice of this region as final landing site for the Mars Exploration Rover Opportunity. Multiple additional minerals have since been detected in the region, both from orbit and in situ. The present paper reasses…
Gale crater and impact processes - Curiosity's first 364 Sols on Mars
Bridges, Nathan T.; Mangold, Nicolas; Wiens, Roger C. +18 more
Impact processes at all scales have been involved in the formation and subsequent evolution of Gale crater. Small impact craters in the vicinity of the Curiosity MSL landing site and rover traverse during the 364 Sols after landing have been studied both from orbit and the surface. Evidence for the effect of impacts on basement outcrops may includ…
Cloud structure and composition of Jupiter's troposphere from 5- µ m Cassini VIMS spectroscopy
Fletcher, L. N.; Irwin, P. G. J.; Giles, R. S.
Jupiter's tropospheric composition and cloud structure are studied using Cassini VIMS 4.5-5.1 µ m thermal emission spectra from the 2000-2001 flyby. We make use of both nadir and limb darkening observations on the planet's nightside, and compare these with dayside observations. Although there is significant spatial variability in the 5- &mic…
Vertical propagation of planetary-scale waves in variable background winds in the upper cloud region of Venus
Futaana, Yoshifumi; Imamura, Takeshi; Kouyama, Toru +2 more
Recently it was found that the low-latitude zonal wind and the amplitudes of Kelvin and Rossby waves at the cloud top of Venus show long-term variations in a synchronized manner. For the purpose of explaining this synchronization, we investigated the influence of the background zonal wind profile on the upward propagation of Kelvin and Rossby wave…
Interannual and seasonal changes in the north polar ice deposits of Mars: Observations from MY 29-31 using MARCI
James, P. B.; Cantor, B. A.; Calvin, W. M. +1 more
The MARCI camera on the Mars Reconnaissance Orbiter provides daily synoptic coverage that allows monitoring of seasonal cap retreat and interannual changes that occur between Mars year (MY) and over the northern summer. The northern seasonal cap evolution was observed in MY 29, 30 and 31 (12/2007-04/2012). Observation over multiple Mars years allo…
The mutual orbit, mass, and density of the large transneptunian binary system Varda and Ilmarë
Roe, H. G.; Trujillo, C. A.; Thirouin, A. +7 more
From observations by the Hubble Space Telescope, Keck II Telescope, and Gemini North Telescope, we have determined the mutual orbit of the large transneptunian object (174567) Varda and its satellite Ilmarë. These two objects orbit one another in a highly inclined, circular or near-circular orbit with a period of 5.75 days and a semimajor axis of …
Saturn kilometric radiation periodicity after equinox
Gurnett, D. A.; Kurth, W. S.; Ye, S. -Y. +2 more
The rotation period of Saturn's magnetosphere was found to vary with time, and changing periodicities were identified in magnetic fields, radio emissions, and charged particles. Here we analyze the varying period of Saturn kilometric radiation (SKR) from 2009 to early 2013, i.e. mainly after Saturn equinox of August 2009. A periodicity analysis is…
Extensive Middle Amazonian mantling of debris aprons and plains in Deuteronilus Mensae, Mars: Implications for the record of mid-latitude glaciation
Head, James W.; Baker, David M. H.
The mid-latitudes of Mars are host to a record of recent episodes of accumulations of ice-rich materials. The record includes debris aprons, interpreted to be debris-covered glaciers, that may represent the preserved remnants of a much more extensive ice sheet. We assessed the possibility of former glacial extents by examining debris aprons and th…